A prober is known as a device for inspecting electrical characteristics of a semiconductor device, e.g., a power device or a memory, formed on a semiconductor wafer (hereinafter, referred to as “wafer”) as a substrate. The prober includes a probe card having a plurality of probe needles and a vertically movable stage on which a wafer is mounted. Electrical characteristics of the semiconductor device are inspected by bringing probe needles of a probe card into contact with solder bumps or electrode pads of the semiconductor device and allowing an inspection current to flow from the probe needles to the electrode pads or the solder bumps. The prober has a test head for determining a quality of the semiconductor device based on the inspection result of the electrical characteristics of the semiconductor device by the probe card (see, e.g., Patent Document 1).
A semiconductor device for vehicle mounting is used under a severe environment and, thus, an operation of the semiconductor device needs to be ensured under the severe environment. Accordingly, the prober may inspect electrical characteristics of the semiconductor device under a high-temperature environment where the wafer is heated. When an inspection current is made to flow through an inspection circuit of a power device or made to simultaneously flow through inspection circuits of a plurality of memories formed on a wafer, the amount of heat generated from the wafer is increased. Therefore, the electrical characteristics of the semiconductor device may be inspected while cooling the wafer.
To do so, in a conventional prober, a stage 70 has therein a heater 71 and a medium channel 72 passes through the stage 70, as shown in FIG. 9. A low-temperature medium is supplied from a chiller 73 to the medium channel 72. By controlling ON/OFF of the heater 71 or the amount of the low-temperature medium supplied to the medium channel 72, a wafer W mounted on the stage 70 is heated or cooled.
Patent Document 1: Japanese Patent Application Publication No. H7-297242
However, the prober shown in FIG. 9 is disadvantageous in that when the chiller 73 supplies a medium having a low temperature, e.g., about −30° C., to the medium channel 72 in order to cool the wafer W whose temperature has been increased to a high temperature, e.g., about 95° C., by the flow of the inspection current to the inspection circuit of the power device, hunting of the temperature of the stage 70 occurs due to a difference between a desired temperature and the temperature of the low-temperature medium and, thus, it is difficult to maintain the wafer W at the desired temperature.
In order to suppress the hunting of the temperature of the stage 70, it is attempted to supply a medium having a comparatively high-temperature, e.g., about 75° C., to the medium channel. Since, however, it is general that the chiller 73 does not change the temperature of the supplied medium, the temperature of the wafer W may become close to the desired temperature depending on a heat transfer condition between the wafer W and the stage 70 but cannot reach the desired temperature.
In other words, in the prober, it is difficult to control the temperature of the wafer W to a desired level when electrical characteristics of the power device or the memory of the wafer W.